Sanding machine and method of sanding ceramic ware



Oct. 10, 1944. H, v. SCHWEITZER 2,359,879- SANDING MACHINE AND METHOD OFSANDING CERAMIC WARE Filed Dec. 28, 1943 2 Sheets-Sheet 1- INVENTOR vHarm/90 1/. Saws/725A 1944- H. v. SCHWEITZER ,3595

SANDING MACHINE AND METHOD OF SANDING CERAMIC WARE Filed Dec. 28, 1943 2Sheets-Sheet 2 INVENTOR. flan m0 M jCHWE/TZE/E' v Patented Oct. 10, 1944UNITED STATES PATENT OFFICE SANDING MACHINE AND METHOD OF SANDIN GCERAMIC WARE Howard V. Schweitzer, Shaker Heights, Ohio ApplicationDecember 28, 1943, Serial No. 515,896

11 Claims.

This invention relates to an improvement in sanding machines and, moreparticularly, to a machine for sanding green dish and similar ceramicware to prevent warping and sagging in the bisque fire.

Heretofore sanding has been a relatively slow and'dusty operation,performed largely by hand. To sand dish ware, for example, a hung ofware was placed within a flask on a table; sand was shoveled into theflask to surround and cover the ware, care being exercised to avoiddisplacing the alignment of the dishes in the hung; the table was thenshaken until, in the judgment of the operator, the sand would besuillciently compasted between the rims of the dishes and setter makingup the bung; the flask was then removed and the sanded bung was removedand placed in a sagger for firing.

The prior practise as outlined above was never wholly satisfactory. Ifone dish in the bung were displaced by careless loading of the flask,not only the displaced dish but other dishes might be warped when fired.Even if the bungs were not disturbed, there was no uniformity in thedegree to which the sand was packed in the bung, thus resulting in alack of uniformity in the fired ware.

It is an object of this invention to provide a machine which willuniformly sand bungs of green were without disturbing the bungs. It isanother object of this invention to provide a machine which willeliminate the laborious hand operations of the prior practise and whichwill require only unskilled operators to load and unload the machine, Aparticular advantage of my invention is that two unskilled operatorsworking on my machine can produce a better product at a production rateequal that of many semi-skilled operators following the prior artpractise.

Other objects and advantages of my invention will be apparent from thefollowing specification, claims, and drawings, in which:

Fig. 1 is a. side elevation showing in operation a machine embodying myinvention.

Fig. 2 is a plan view taken along the line 22 of Fig. l but from whichthe fugitive elements of sand and ware have been eliminated.

Fig. 3 is an enlarged detail section and elevation taken along the line3-3 of Fig. 1.

The machine in the embodiment of my invention disclosed is comprised ofa frame having parallel horizontal members H) which extend the length ofthe machine. The frame members l support a larg fiat driving pulley ii,adjacent the discharge end of the machine, and a similar largeflat-idler pulley l2, at the loading end of the machine. The idlerpulley i2 is mounted in adjustable bearings I3 to regulate tension inthe endless flat flexible conveyor belt l5 carried by the pulleys H andII. The driving pulley II is mounted in fixed bearings I4 and is drivenby any'suitable speed-change drive, such as the reduction gearing unitI3, driven by the motor I! through the expansible V-belt pulley l8. Thespeed of the conveyor belt is varied by operating the handwheel IQ ofthe motor platform feed screw to vary the distance between the shaft ofthe motor I! and the shaft of the expansible V- belt pulley l8 andthereby vary the eifective driving diameter of the pulley l8.

The upper conveying run of the belt I5 is supported in the centerportion of the run by the several troughing rolls 20 to form the belt l5into a flat bottomed trough. Between the troughing rolls 20 and flatpulleys II and [2 the belt is supported by the fiat rolls 2| and 22. Theunder or return run of the belt i5 is suitably supported by the rolls23.

A longitudinally extending sand hopper 30 is supported and approximatelycentered over the belt I5 adjacent the loading end of the machine. Inthe embodiment disclosed, a partition 3| in the lower portion of thehopper 30 divides the hopper into a light sanding section 32 and a heavysanding section 33, the light sanding section being located toward theloading end of the machine. The hopper sections 32 and 33 to the hopper30 from the sand reservoir 38.,

By regulating the opening of the gate 34 so that sand will run from thesection 32 at aslow rate of discharge and by opening the gate 35 so thatsand will run from the section 33 more rapidly, sand is first fed ontothe belt i5 rather slowly and lightly and then rapidly and heavily asthe belt progresses under the hopper. To obtain a more gradual change inthe rate of feed of sand onto theconveyor belt IS, the number of gatesmay be increased or the hopper may be closed by a plate adjusted so thatthe discharge slot from the hopper will be narrow toward the loading endof the machine and wider toward the discharge end. The end wall oihopper 30 located adjacent the loading end of the machine is providedwith a tailpiece 39 which prevents a rapid flow of sand from the openend of the gate 34. In the embodiment disclosed, the partition 30 isprovided with a similar tailpiece 38.

Sand fed onto the belt I! is discharged at the discharge end of theconveyor into a collecting hopper 40 having a sloping bottom leading toa sump 4i. Sand which may fall of! the sides of the belt I! as the beltflattens in approaching the driving pulley l l is caught in suitablegutters 42 leading to the collecting hopper 4U. Ware carried by the belti5 is fed onto a suitable grid 45 which is substantially coplaner withthe flat center portion of the belt IS. A vertically adjustable scraper41 extends transversely over the belt adjacent the discharge end of themachine. Sand collected in the sump 4I.may be returned to the reservoir38 by any suitable sand elevating and conveying means (not shown). If itis desired to avoid placing the sump below the floor level, as in the embodiment disclosed, and if the height of the machine is insumcient topermit the bottom of the collecting hopper to be set at sufflcientangularity to allow the sand to flow into the sump by gravity, thesloping bottom of the collectin hopper may be provided with vibrators orsimilar feed means to cause the sand to flow into the sump.

Located between a pair of troughing rolls beyond the sand hopper 30 area pair of transverse beams 5| which support the vibrator plate 50through the springs or similar resilient means 52, which urge the plate50 against the underside of the central fiat portion of the troughedbelt l5. The plate 50 and the .portion of the flexible belt l5 whichrests upon the plate are vibrated by the electrical vibrator 55 securedto the underside of the floating vibrator plate 50. In order to reducethe load on the spring. guide pins 53, which confine the plate 50 tosubstantially vertical motion, it is preferable that the vibrator 50 bea synchronous magnetic. vi-

brator rather than a vibrator which operates by virtue of a rapidlyrotated eccentric weight. The cord 56, therefore, preferably connectsthe .vibrator 55 to a suitable source of alternating current.

To employ my machine for sanding ware, a bung of green ware, comprisinga plurality of dishes stacked foot-in-well on a refractory or othersuitable setter, is placed upon the center portion of the conveyor beltl5 at the loading end of the machine. With the gates 34 and 35 set todischarge sand at the desired rate, as the bung of ware is carried underthe section 32 of the hopper the bung is sanded lightly. The

sand first forms a cone on the top dish and a after the cone on the topdish reaches its maximum altitude, sand builds up around the base of thebung; simultaneously the sides of the conveyor belt are gradually liftedup in approaching the first troughing roll, thus preventing sand fromrolling of! the belt and instead, holding the sand against the .base ofthe bung. By the time the bung has reached the first troughing roll andthe portion of the belt supporting the bung has passed over the flatrollers 22, the base of the bung is sufllciently surrounded by sand toprevent the bung from being displaced by the slight but appreciablevibrations encoun tered as the belt passes over the more widely spacedtroughing rolls 20, the run of the belt over the closely spaced flatrollers 22 being relatively vibrationless.

As the bung passes the first troughing roll,

the bung is sumciently supported to withstand a more rapid loading ofsand and the bung, therefore, is carried under the heavy sanding section33 of the hopper 30. when the bung is carried beyond the hopper 30, thebung is completely buried under the mound of sand discharged onto theconveyor belt II. It should be noted that as the increasingly loadedbelt passes over the troughing rollers 20 located un-q der the hoppersection 33, the slight vibrations imparted by the troughing rollers andthe bellying of the sides of the belt between the troughing rollers willtend to gently work the sand around the bung.

As thebung passes beyond the hopper 30, the center portion of the beltupon which the bung rests is slid upon and over the rapidly vibratingvibrator plate 50. The intense rapid vibrations (usually 60 cycles persecond) imparted to the belt I5, the bung, and the covering mound ofsand thoroughly and uniformly packs the sand between the rims of thedishes in the bung, as shown in Fig. 3 of the drawings. The amplitude ofthe vibrations may be varied by a suitable rheostat or like control (notshown).

From the vibrator plate 50 the bung is carried beyond the troughingrolls and approaches the discharge end of the machine, the coveringmound of sand falling away from the bung as the sides of the belt arelowered in leaving the last troughing rolls and approaching the drivingpulley I I. At the discharge end of the machine, the sand (except thatsupporting -the rims of the dishes in the bung) is discharged into thehopper 40 and the sanded bung is fed onto the grill 45, from which thebung is lifted oil? to be loaded into the saggers for firing.

In order to remove the cone of sand which would otherwise remain on thebung at the discharge end of the machine, the scraper 41 is adjusted sothat its lower edge will clear the top dish as the bung passes under thescraper. The scraper 47 is particularly useful when the machine is usedfor several hours or more to sand were of the same size and,consequently, being stacked in bungs of approximately equal height. If,as is often the case, the machine is loaded with bungs of differentheights, the scraper is set for the tallest bungs or removed altogether,

the cones of sand on top of the bungs being brushed oil by hand as thebungs are picked up from the grill 45.

The speed 'at which the belt l5 travels is adjustd so that each bungwill remain over the vibrator plate 50 the desired length of time tothoroughly pack the sand in the bung. Once this speed'has beendetermined for a particular run of ware being sanded, it is unnecessaryto change it, and, because the speed of the belt is constant, each bungoi ware sanded during the run remains over the vibrator plate preciselythe same length of time. Thus, all ware is uniformly sanded. In thepractical operation of the machine, it is seldom, if ever, necessary tovary the speed of the belt between runs.

The only remaining adjustment to be made on the machine is that of thehopper gates 34 and 35, which are adjusted to discharge sand so that anadequate amount or sand will be discharged from the light sandingsection 32 to support the bungs for the loads of sand discharged fromthe heavy sanding section 33, the amount of sanddischarged from thesection 33 being such that the largest bung in the run or ware beingsanded assume will be covered after passing over the vibrator plate It.

From the foregoing, it is apparent that only three adjustments arenecessary for the operation of my machine and that such adjustments maybe made by a foreman at the start oi each run. No skill on the part ofthe loader is required in loading sand around an unsanded bung. Nor isany skill required on the part of the unloader in removing sand fromaround a sanded bung. Because the grill 45 permits sand to fall awayfrom a sanded bung, the unloader simply picks up a bung by the setter.The possibility of disturbing a hung while removing excess sand aroundthe bung is thereby eliminated. Thus, only unskilled labor is needed toload and unload the bungs of ware during the operation of the machine.My machine greatly reduces the amount of time heretofore required forthe sanding operation. In normal operation, the machine will sand bungsas fast as an operator can conveniently unload the machine. Due tothisincrease in output per operator, the sanding operation is greatlyreduced in cost.

In the foregoing specification I have disclosed a preferred embodimentof my invention. It is to be understood, however, that my invention isnot limited to the embodiment disclosed but may be modified within thescope of the following claims. It is to be understood that in thefollowing claims the term sand includes not only the common silica sandbut also dry powdered flint, clay, or like pulverant material employedto pack ware prior to firing.

What is claimed is:

1. In a machine for sanding ceramic ware, a'

ware conveyor for conveying ware from a loading station to an unloadingstation, means to deposit sand on said conveyor to cover ware conveyedby said conveyor, and means to vibrate said conveyor after ware has beencovered with sand to pack the sand around the ware, the ware beingremoved from saidconveyor at the unloading station of said conveyor.

2. In a machine as defined in claim 1, means to receive sand dischargedfrom said conveyor at the unloading station.

3. In a machine for sanding ceramic ware, a ware conveyor for conveyingware from a loading station to an unloading station, means for drivingsaid conveyor, said conveyor being comprised of a center ware-conveyingportion which travels between said stations substantially in a singleplane and side portions elevatable above the plane of said centerportion, means for depositing sand on said center portion in a moundhaving its apex located vertically above said center portion, meanslocated between said stations for elevating said side portions to imparta flatbottomed trough-shaped cross section to said conveyor, a vibratorto compact sand carried by said conveyor, means to remove sand from saidconveyor at said unloading station, and means to receive sand removedfrom said conveyor.

4. A machine as defined in claim 3 in which said conveyor is an endlessconveyor in which the run from the loading station to the unloadingstation is the upper horizontal run of the conveyor and in which themeans for removing sand at the unloading station comprises a pulley overwhich the conveyor is turned from its upper run to its lower return run,and a grill to receive bungs of ware from the conveyor and to allowexcess sand to fall away from the buhgs.

5. In a sanding machine for ceramic ware, an

endlessflexible conveyor belt, a flat horizontal driving pulley. a flathorizontal idler pulley spaced from said driving pulley, said belt beingsupported by said pulleys to provide an upper horizontal conveying runand a lower horizontal return run, said conveying run having a loadingstation adjacent the commencement of the conveying run and an unloadingstation adjacent the end of the conveying run, troughing rollssupporting said conveyor run of said belt intermediate of said stationsand forming said belt into a trough having, a flat-bottom centerware-conveying section, a hopper having a discharge opening extendinglongitudinally of. ,the conveyor run of said belt and located verticallyabove the center section of said belt, whereby sand'discharged from saidhopper will form a horizontal mound on said conveyor, the end of saidhopper nearer the unloading station being located above said troughingrolls, a vibrator plate located beneath the center section of saidconveying run of said conveyor and adjacent the end of said hoppernearer the unloading station, resilient means urging said vibrator plateinto engagement with the under surface of said belt, a vibrator tovibrate said vibrator plate, and means to collect sand discharged bysaid belt adjacent the end of the conveyor run.

6. In a sanding machine for ceramic ware, an endless flexible conveyor,a horizontal driving pulley, a parallel idler pulley, said conveyorbeing supported by said pulleys to provide an upper horizontal conveyingrun and a lower return run, means to drive said driving pulley, saidconveying run having loading and unloading stations adjacent thecommencement and end, respectively, of the conveying run, troughingrolls supporting the conveying run intermediate of said stations andforming said conveyor into a trough having a center ware-conveyingsection, a hopper having a discharge opening located vertically abovethe center section of said conveyor, whereby sand discharged from saidbelt will form a mound on said conveyor, the end of the hopper locatednearer the unloading station-being located above the trough formed inthe conveying run, a vibrator plate located beneath the center sectionof the conveyor run and adjacent the end of the hopper nearer theunloading station, resilient means urging said vibrator plate intoengagement with the under surface of said conveyor, a vibrator tovibrate said plate, means to control said belt drive and means tocontrol the operation of said vibrator, whereby operation of saidcontrol means controls the compacting of sand around ware carried bysaid conveyor, and means to collect sand discharged from said conveyoradjacent the end of the conveyor run.

7. In a machine as defined in claim 5, a scraper extending transverselyof said belt adjacent the unloading station and fixed relatively to thelength of said conveyor run, and means to adjust the vertical distancebetween said scraper and the ware-conveying portion of said belt.

8. A method of sanding ceramic ware comprising the steps of placing abung of ware in the center-of a flexible sheet, pouring sand on ware atincreasing rates until said bung is buried in said sand, raising themarginal portions of said sheet as sand is poured on said bung tomaintain said sand around said bung, flexing said margin portions ofsaid sheet to work said sand surrounding said bung, vibrating saidcenter portion of said sheet to compact sandginto the external openingsbetween ware in saidbung, and then lowering said marginal portions touncover said bung.

9. In a sanding machine for ceramic ware, a conveyor having a conveyingrun and loading and unloading stations adiacent the beginning and end orthe conveyor run, said conveyor including an endless flexiblesand-supporting belt and a pair of pulleys supporting saidsand-supporting belt, a hopper having a discharge opening locatedcentrally above said belt to discharge sand thereon, means supportingsaid belt intermediate said pulleys to maintain said belt substantiallylevel under the load of sand discharged thereon, a vibrator plateengaged against the .under surface of said belt and adjacent thedischarge opening of said hopper, a vibrator connected to said plate tocompact sand carried by said belt, means extending beyond said belt tosupport ware carried by said conveyor and to permit sand to fall awayfrom the ware as the ware approaches the unloading station, and means tocollect sand which falls away from the ware;

10. In a sanding machine for ceramic ware, an endless flexible conveyorbelt, a flat horizontal driving pulley, a ilat horizontal idler pulleyspaced from said driving pulley, said belt being supported by saidpulleys to provide an upper horizontal conveying run and a lowerhorizontal return run, said conveying run having a loading stationadjacent the commencement of the conveying run and an unloading stationadjacent the end of the conveying run, troughing rolls supporting saidconveyor run of said belt intermediate of said stations and forming saidbelt into a trough having a flat-bottom center ware-conveying section, ahopper having a discharge opening extending longitudinally of theconveyor run of said belt and located vertically above the centersection of said belt, means to vary the width of said opening to depositsand on said conveyor at an increasing rate as said conveyor advancestoward the unloading station, whereby sand is first lightly and finallyheavily discharged from said hopper to form a horizontal mound on saidconveyor, the end of said hopper nearer the unloading station assurebeing located above said troughing rolls, a vibrator plate locatedbeneath the center section of said conveying run or said conveyor andadiacent the end of said hopper nearer the unloading station, resilientmeans urging said vibrator plate into engagement with the under suriace01 said belt, a vibrator to vibrate said vibrator plate, and

means to collect sand discharged by said belt.

adjacent the end of the conveyor run.

11. In a sanding machine for ceramic ware, an endless flexible conveyorbelt, a flat horizontal driving pulley, a flat horizontal idler pulleyspaced from said driving pulley, said belt being supported by saidpulleys to provide an upper horizontal conveying run and a lowerhorizontal return run, said conveying run having a loading stationadjacent the commencement of the conveying run and an unloading stationadjacent the end of the conveying run, troughing rolls supporting .saidconveyor run of said-belt intermediate of said stations and forming saidbelt into a trough having a flat-bottom center ware-conveying section, ahopper having a discharge opening extending longitudinally of theconveyor run of said belt and located vertically above the centersection of said belt, a plurality of gates for closing said hopperdischarge opening, said ates being located longitudinally of the hopperwith respect to 'each other, and means to vary the degree to which eachof said gates closes its hopper discharge opening, whereby sand may bedischarged from said'hopper to form. a horizontal mound on said conveyorat a varying rate, the end of said hopper nearer the unloading stationbeing located above said troughing rolls, a vibrator plate locatedbeneath the center section of said conveying run of said conveyor andadjacent the end of said hopper nearer the unloading station, resilientmeans urging said vibrator plate into engagement with the under surfaceor said belt, a vibrator to vibrate said vibrator plate, and means tocollect sand discharged by said belt adjacent the end of the conveyorrun.

HOWARD V. SCHWF-ITZER.

